Firefox 5 has this ANNOYING offline cache storage which does not get cleared when you clear cookies and cache the normal way. I wasted two hours of my time because when I made changes to my htaccess file for a rewrite the change would apply to Chrome and IE but not firefox. I tested n different regexes in my htaccess thinking it was a problem with my htaccess code.

Finally hours later googling made me realize that firefox caches htaccess and other things not in the traditional cache but in a separate place. To clear that you have to go to Options->Network->Offline Storage->Clear Now